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From Jeremy Hanna <jeremy.hanna1...@gmail.com>
Subject Re: Massive writes when only reading from Cassandra
Date Sat, 10 Sep 2011 20:56:49 GMT
Oh and we're running 0.8.4 and the RF is 3.

On Sep 10, 2011, at 3:49 PM, Jeremy Hanna wrote:

> In addition, the mutation stage and the read stage are backed up like:
> 
> Pool Name                    Active   Pending   Blocked
> ReadStage                        32       773         0
> RequestResponseStage              0         0         0
> ReadRepairStage                   0         0         0
> MutationStage                   158    525918         0
> ReplicateOnWriteStage             0         0         0
> GossipStage                       0         0         0
> AntiEntropyStage                  0         0         0
> MigrationStage                    0         0         0
> StreamStage                       0         0         0
> MemtablePostFlusher               1         5         0
> FILEUTILS-DELETE-POOL             0         0         0
> FlushWriter                       2         5         0
> MiscStage                         0         0         0
> FlushSorter                       0         0         0
> InternalResponseStage             0         0         0
> HintedHandoff                     0         0         0
> CompactionManager               n/a        29
> MessagingService                n/a      0,34
> 
> On Sep 10, 2011, at 3:38 PM, Jeremy Hanna wrote:
> 
>> We are experiencing massive writes to column families when only doing reads from
Cassandra.  A set of 5 hadoop jobs are reading from Cassandra and then writing out to hdfs.
 That is the only thing operating on the cluster.  We are reading at CL.QUORUM with hadoop
and have written with CL.QUORUM.  Read repair chance is set to 0.0 on all column families.
 However, in the logs, I'm seeing flush after flush of memtables and compactions taking place.
 Is there something else that would be writing based on the above description?
>> 
>> Jeremy
> 


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